Multiway electrical connectors are well known. These connectors are made of a rigid material and includes a plurality of cavities in a back end for receiving a plurality of electrical wires ended by crimped terminal fittings. At their front ends, these connectors are provided with female or male connecting elements for receiving a complementary counterpart connector. Between these two ends, channels extend between corresponding cavities, for receiving the said electrical wires.
Usually, a one-piece or integral resilient mat seal is sandwiched between a front part and a rear part of the connector. The mat seal has a plurality of channels such that, when the mat seal is mounted in the connector, each channel of the mat seal faces an associated channel of the connector.
During the insertion of the electrical wires in the channels of the rear part of the connector, the channels of the mat seal are passed by the plurality of terminal fittings that are then housed in the channels of the front part of the connector. The said terminal fittings are then at the neighboring of the front end of the connector.
The channels of the mat seal are further arranged for tightly maintained the electrical wires.
This resilient mat seal is thus preventing moisture and dust by entering the connector.
It is known by example from EP 0 625 807 to obtain a good tight contact between the electrical wires and the mat seal, by providing the surfaces of the channels with lips extending inwardly. These lips allow the passage of the terminal fittings and then press the electrical wires, when the terminal fittings are passed. The tightness is then ensured.
A problem raised by this kind of mat seal is that, if the cross-section of the wires is not substantially the same as those of the terminal fittings, the passage of the terminal fittings stress the said lips. The latter cannot then press efficiently the wire for ensuring a sufficient tightness.
Additionally, there is a need for mat seals adapted for receiving wires having different cross-sections.
US 2005/0118850 attempts to solve these problems by firstly proposing a mat seal having the following two different types of channels:                channels having lips extending inwardly from their surface;        channels having smooth surface.        
Channels of the first type are designed for receiving wires having small cross-sections. The principle is the same as those disclosed in EP 0 625 807.
Channels of the second type are designed for receiving wires having large cross-sections.
In this second type, a portion of the outer surface of the wires is surrounded with a resilient sealing sleeve. This sealing sleeve has lips extending outwardly from its outer surface. The mat seal has further a cross-section equal or greater than the terminal fittings.
The passage of the terminal fittings is then not aggressive to the smooth surface of the mat seal channels, the tightness being then ensured by the pressure of the lips of the sealing sleeve to the smooth surface of the corresponding channels.
Additionally, this tight assembly can provide a tight contact for two wires having different cross-sections.
But the problem stays the same for the wires with small cross-sections.
Additionally, it would be grateful to provide a mat seal having channels designed so that each one can receive wires with different cross-sections.
WO 2004/025787 proposes a tight assembly wherein wires having different cross-sections can be tightly secured in one channel of a mat seal.
This channel has the two following portions:                a front portion with a smooth surface;        a rear portion provided with lips extending inwardly from the smooth surface.        
Wires having large cross-sections are tightly secured at the channel rear portion.
Wires having small cross-sections are provided, on a portion of their outer surface, with sealing sleeve having lips extending outwardly from its outer surface. These wires are then tightly secured at the channel front portion by the lips of the sealing sleeve which are tightly secured at the smooth channel rear portion.
An objective of the invention is to propose a low-cost and easier tight assembly to manufacture, which overcomes the foregoing problems.
A particular objective of the invention is to propose a tight assembly that can ensure the tightness of an electrical connector, that can be used for different cross-sections of electrical wires to connect.
For this purpose, this invention proposes a assembly for an electrical connector comprising:                a resilient mat seal having two main surfaces and a plurality of channels extending between said two main surfaces, each being intended to receive a respective electrical wire, and wherein an annular sealing lip is provided within each channel and extends from the channel wall towards a center axis of said channel; and        at least one sealing sleeve entirely surrounding a portion of an electrical wire to be introduced in one of said channels and tightly maintained on said wire;wherein the sealing sleeve has at least a portion with a smooth outer surface and an outer cross-section of said portion chosen such that said portion of the sealing sleeve and the channel lip are in tight engagement with each other when the wire provided with said sealing sleeve is positioned in its respective channel.        
Other characteristics of this tight assembly are:
it further comprises at least one electrical wire and one terminal fitting fixed to each electrical wire, wherein the said sealing sleeve surrounded the portion of the electrical wire neighboring the terminal fitting;
it further comprises at least one electrical wire which is not surrounded by the said sealing sleeve, wherein the cross-section of this electrical wire is substantially the same as the cross-section of the said sealing sleeve;
the sealing sleeve is partly hold by the terminal fitting;
the mat seal is integrally molded.
According to a second aspect, the invention proposes an electrical connector intended to be connected to a counterpart electrical connector along a plugging axis, comprising:                a plastic housing provided with a plurality of channels extending parallel to the plugging axis, the plastic housing having a front part and a rear part mounted together, the front part having a front face provided with metallic pins or crossing holes for respectively receiving holes or pins of the counterpart electrical connector;        a resilient mat seal between the front part and the rear part of the plastic housing, the resilient mat seal having two main surfaces and a plurality of channels extending between said two main surfaces and corresponding to the channels of the plastic housing, and wherein an annular sealing lip is provided within each channel and extends from the channel wall towards a center axis of said channel;        electrical wires engaged in said channels of the plastic housing and in said channels of the mat seal;        
at least one sealing sleeve entirely surrounding a portion of at least one electrical wire engaged in one of said channels and tightly maintained on said wire, wherein the sealing sleeve has at least a portion with a smooth outer surface and an outer cross-section of said portion chosen such that said portion of the sealing sleeve and the channel lip are in tight engagement with each other when the wire provided with said sealing sleeve is positioned in its respective channel.
Another characteristic of this electrical connector is:
the electrical wires are fixed to metallic terminal fittings.